Sustainable development goals are currently aimed at reducing carbon dioxide (CO2) emissions generated worldwide. Hydrogen is an energy path of significant impact, which can be obtained through the electrolysis of water and fulfill the function of fuel. The purpose of this work is to develop an experimental testbed to obtain oxyhydrogen through the electrolysis process of saline water for the hybrid fueling of a four-stroke engine. The case studies analyze a pair of hydrogen cells configured with 9 and 37 plates, showing that energy efficiency can be improved by maintaining a constant flow supplying the 37-plate cell while keeping a four-stroke engine working and stable with the mixture of fossil fuel and oxyhydrogen. The results show the operation of the engine, obtaining a graph of energy efficiency versus power values and a graph of energy efficiency versus current. This research project demonstrated that the testbed can be utilized to acquire the correct values of oxygen necessary to ignites a four-stroke engine.